The tensioning of the rods can be done by applying a tightening torque to nuts resting axially on the surfaces of the structures to be tightened. The tensioning rod device exerts an axial tensile for to one end of the threaded rod by means of a tie-rod. The device rests on a surface of a structure to be tightened by means of a tubular support sleeve surrounding an end of the threaded rod. The device provides a cylinder, and a piston sliding in the cylinder and forming with the cylinder an annular chamber dedicated to be fed with pressurized fluid.
The rod is tensioned by means of the piston pressurized and is stretched. The rod is then locked by means of a nut for example, directly on the rod or on the device itself. The released rod tends to recover its resting length but is blocked by the nut. The released rod then exerts a tightening force on the mechanical parts to tighten. Such tightening method is an advantageous alternative to tightening a nut to which an important tightening torque is to be applied.
Such known rod tensioning device, for example disclosed in EP 2 361 722 B1, is designed to be used in opened spaces and are easy to install. However, such tensioning device may not be suitable for use in a reduced space for mechanical structures requiring an important tensioning axial force.
More precisely, the tensioning axial force exerted by such tensioning device depends on the pressure surface of the chamber between the piston and the cylinder. A rod tensioning device as known and of reduced dimensions, for example for being installed in a reduced space, implied a reduced potential tensioning axial force.
Moreover, the rod tensioning device as known cannot be installed in places of reduced axial dimensions, in particular between a first structure from which axially protrude a rod and a second structure that is axially close to the free end of the protruding rod.